What would you say to a young (adult), polyam, sub/little one who absolutely is so happy, loves to be submissive and is honored to have their Daddy/Dom… but who also craves and constantly wonders about being mentored and under the rule of an older and experienced Dom for both the learning; as well as the exciting factor.. -from a guilty and lost subby/baby (They/them pronouns only)

I’m going to key off the “guilty” part for a second.  The clearest description of cheating I ever heard was “changing the rules without telling the other players.”   I’m sure it would be educational and exciting to have a mentor if you were single, or if you and your partner had an agreement.  

I think the first thing any good mentor would do is make sure you were in integrity with your partner.

I’m not saying that to be mean or judgmental – fantasies are awesome!  But an authentic real-life mentor would keep his pants in, and yours, and help you stay oriented towards your partner.